Field of the Invention: This invention concerns the melting and the refining of glass and is particularly directed to devices for stirring molten glass to homogenize it prior to its being fully refined.
Brief Description of the Prior Art: Glass stirring devices are well known and have been employed in the past for homogenizing molten glass. They have been used particularly in optical glass manufactureand in the forehearths of glassmaking furnaces to stir glass immediately prior to discharge of the glass for forming into useful glass articles. Two U.S. Pat. Nos. 2,022,223 to Taylor and No. 2,049,600 to Wright disclose the use of devices for contacting molten glass in the relatively narrow waists of continuous glassmaking furnaces. The device of Wright is located in a continuous glassmaking furnace shown to be employed for discharging molten glass to the drawing kiln of a glass sheet drawing process. It comprises, not a stirrer per se, but rather a barrier which is intermittently placed in the molten glass to retard the surface flow of the glass and permit the accumulation of floating impurities behind the device which is periodically lifted to allow the accumulated floating impurities to pass downstream through the furnace and into the working zone of the drawing kilm attached thereto. The patent to Taylor, however, discloses a pair of rotating stirrers comprising cooled fingers having bent refractory thimbles attached to their working ends. The thimbles are used to homogenize the molten glass by engaging the glass from each side of the furnace waist and stirring the glass.
A number of patents disclose the use of molten glass stirrers in the forehearths of glassmaking furnaces rather than in the waists of furnaces. These patents illustrated several particular stirrer structures. Inparticular, U.S. Pat. No. 2,982,522 to Hamilton et al shows a stirrer which may be rotatated to homogenize molten glass. The stirrer of Hamilton et al comprises a coaxial pair of pipes providing a stirrer shaft. Extending outwardly from the lower end of the shaft are coaxial pipe extensions. The stirrer may be cooled by the introduction of coolant into the annular space and though the inner pipe of the stirrer during use. The present invention, as will be described further below, provides water cooled glass stirrers which are suitable for use in the waist between the melter and the refiner of a glassmaking furnace which are useful together with a plurality of similar stirrers aligned across the width of such a furnace waist in closely spaced relation to one another.